In a rash moment, because I cannot cook very well, I invite an American paediatrician to dinner. He's a sort of colleague who has been to England many times before. If I had been even once to Boston he would have held a party for me or at least had me over for dinner. Suddenly ashamed that I have never even offered him a cup of tea, I invite him over. I'm also interested in watching how a paediatrician behaves with kids.

So B comes over. I've remembered that I can cook something – lasagne, and what's more I did it earlier while Flora was asleep, so when B gets to our house I manage to show him I can look after the children and give him something to eat.

B, it turns out, has a direct approach with children. He introduces himself to them in a loud voice and wades right in. "How did you feel when your mother became pregnant?" he asks Tilly, who is 11. I wait for Tilly to use a variation of her new word – "degrading", which she applies to almost everything I do, but she merely tells him it was a little strange.

"Do you find you have less time with your mum now she has a baby?" he fires at Lydia, who's eight. Apparently not, as I have noticed her climbing on my bed in the morning to kiss the baby first and me second.

Simultaneously, seeing baby Flora is dribbling, he confidently – and unasked – sticks a finger into her mouth (unwashed I notice) and announces that contrary to what we might think, she is not teething.

It's a good visit, special even, because B says something that sticks in my mind. I can't remember what it was in relation to, but it was the sort of homespun, apple pie philosophy that I'm a sucker for. He said, albeit after a few glasses of wine: "In life, you never regret what you spend or do, only what you don't spend and don't do."

So after dropping him back at the tube station, I decide to do something I have been meaning to do for six years. I decide to take my 86-year-old mother to see the Grand Canyon. My mother has been quietly ticking off the great sights of the world. The Great Wall of China, the Taj Mahal, and the Pyramids. Next stop the Grand Canyon, she has said, before she either goes blind or dies.

There may be a little emotional blackmail in this but I am more than ready to fall for it. Watching her with baby Flora is a rather moving experience. Since the baby arrived, my mother has forgotten any aches or pains she had, she's lost weight from playing "Look, Flora's flying" and looks younger than me (as does everyone). But along with her new found vigour is the awareness, well mine anyway, that unlike with some of her other grandchildren, she's unlikely to live long enough to see Flora grown up. So J and I decide that money is not important and therefore we will all go to see the Grand Canyon with my mum. Sorting out a road trip with a baby one end and an 86-year-old at the other is not easy.

Neither is getting insurance for my mother. No one wants to insure someone who's over 85. "These old people," says one sales person, "when they go on holiday they get a new lease of life and start doing things they don't normally do and then, wham, they've had a blackout."

Our first quote comes in at £700 – at that rate you'd feel obliged to use your health insurance, we decide. But finally we get something that seems fair. So it's off we go on our ridiculous holiday. Friends smile and tell us it will be great. "You never regret what you spend or do," I say to them, wisely. "Only what you don't spend and don't do."